Of the more than 1.7 million estimated people ever infected with HIV in the U.S., new infections are highest among young Latinas and young Black women. HIV incidence rates among youth in the U.S. have either remained constant or are increasing, primarily due to sexual transmission. Given that young people between ages 13-29 have the highest HIV incidence and a substantial need of sexual and reproductive health (SRH) services, and this population has a high smartphone ownership in comparison to other age groups, mobile platforms may offer an effective opportunity to decrease HIV/STI risk behaviors. The development of a smartphone app informed by youth peer educators (18 to 21y.o.) not yet released in the market offers a unique opportunity to conduct an experimental design study to understand how young Latinas and Black women (YLBW) use the app and how it influences knowledge of SRH services. Specifically, the proposed pilot project examines if YLBW ages 18-25 who use a smartphone app for SRH information can achieve increased knowledge and utilization of SRH services such as PEP, Plan B, HIV, STI, and pregnancy testing, and to other social services, such as substance abuse treatment. This pilot project will draw from social cognitive theory, social network theory, and interactive technology pedagogy frameworks to address the following two aims: (1) Identify and explore the settings and situations where participants will use a location enabled SRH smartphone app, and further tailor the app content to meet the needs of the target audience. (2) Pilot an intervention to assess whether access to an SRH smartphone application, including push messages, versus self-directed SRH education improves knowledge and increases the use of SRH services such as Plan B, PEP, HIV, other STI, and pregnancy testing. We propose those with access to an SRH app will have better knowledge and greater use of SRH services. Analysis for the first aim will apply grounded theory and for the second aim, will compare differences between the intervention and comparison arms, and will also include social network analysis. The proposed research and training plans are additionally designed to foster my development as a public health researcher by further strengthening my quantitative, technological, publication, and grantsmanship skill sets in order to launch a successful career as an academic researcher. My career goal is to prepare for a career as an independent HIV/STI/SRH researcher in developing, researching and implementing culturally competent and effective behavioral interventions, in order to make evidenced-based HIV prevention recommendations for young people of color.